13Sr..] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 189 



tectb, the last of which is some distance from the acicular tip. The 

 rostrum is unarmed below. The surface of the carapax, and parts of 

 that of the pleon also, are clothed with very short and dense pub- 

 escence. 



The eyes are much larger than in A.? tridens, nearly spherical, much 

 larger than the slender and nearly cylindrical stalks, and black. 



The proximal segment of the peduncle of the antennula is deeply 

 excavated above and armed with a .slender lateral process tipped with 

 an acicular and slightly out-curved spine, just in front of which there 

 is a similar spine terminating the distal angle of the segment itself. 

 The autennae are very nearly as in A.^. tridens. 



The crowns of the mandibles are as in A. ? tridens, but the palpi 

 differ conspicuously, the proximal segment being slightly shorter and 

 the distal very much longer, nearly as long as the proximal, with the 

 lateral ex])ansion at the base narrow and more prominent, and the 

 distal portion twice as long as broad. The palpus is in fact more like 

 Miers's figure of the palpus of A. Edu-ardsianus than that of JL.? tri- 

 dens. The maxilhie are as in A.'l tridens. The protopod and the two 

 proximal segments of the endopod of the maxilliped are also as in that 

 species, but the third segment of the endopod is less than half as broad 

 as long, the terminal segment is a third as long as the penultimate and 

 scarcely half as broad as long, and the exopod terminates in a short 

 but acuminate, slender, multiarticulate and tlagelliform tip. The endo- 

 pod of the first gnathopod is like that of A.? tridens., but the exopod 

 is large, as in the typical species of Penwus, being nearly twice as long 

 as the endopod, and stout. The second gnathopod is very nearly as in 

 A.? tridens. 



The number and arrangement of the branchiae are the same as in A.? 

 tridens, but the pleurobranchia of the eighth somite is rudimentary and 

 that of the ninth small. There are no exopods at the bases of any of 

 the periEopods, which in other respects are ver}' similar to those of JL.? 

 tridens. 



The general form of the pleon is very similar to that of J..? tridens, 

 but the dorsal spines of the third and fourth somites are very small, no 

 larger than that of the fifth somite, and the pleura of the third, fourth, 

 and fifth are evenly rounded instead of angulated posteriorly. 



The telson is nearly a third longer than the sixth somite, regularly 

 and acutely triangular, dorsally and laterally sulcated to near the very 

 slender and acute tip, and armed with three or four i)airs of lateral 

 spinules which increase in size distally, and of which the last pair are 

 approximately twice their length from the tip. The inner lamella of 

 the uropod is nearly as long as the telson, ovate-lanceolate, and nearly 

 four times as long as broad. The outer lamella is more than a third 

 longer than the inner, more than four times as long as broad, and 

 ovately pointed. 



